What the heck happened??

[RonObvious]

Quick story with two mysteries I'm hoping someone can explain: This past weekend we picked up 6 gallons of hot pressed Marquette juice. TA was a little high, so I figured out that I had to add about 60 grams of calcium carbonate. I planned on using the double-salt technique of de-acidifying, but realized when I got home that I didn't have as much CaCO3 as I thought I had. Woops! So I quickly ordered more with 2 day shipping and figured the juice would be fine for 2 days in its plastic bucket because I had carefully sanitized the bucket and had watched the fellow at the vineyard add sulfite to the juice.

But Monday night (while still waiting for the CaCO3 to arrive) I happened to look at the airlock and saw a bubble. Uh-oh! Must be wild yeast, I thought, so I added more sulfite.

Last night the CaCO3 finally arrived. When I went down to the basement to grab about 2 gallons for the double-salt acid neutralization procedure I noticed it was still fermenting!

MYSTERY #1: What kind of wild yeast survives hot pressing AND two doses of sulfite??

So I ignored the fact that it was already fermenting. Not much I can do about it now, I thought. I grabbed approximately 2 gallons of juice, added the required 60 grams or so of CaCO3, stirred it occasionally for an hour or so, then dumped it back in with the rest of the juice. So far so good.

Here comes the weird part. I also needed to add about 2 lb of sugar to bring it to 23 brix. I weighed the sugar, added some water, microwaved and stirred until it was mostly dissolved, then let it cool to just above room temperature. As soon as I dumped the sugar water into the juice - BAWHOOSH! Juice foaming like crazy, pouring over the sides of the bucket, making a HUGE mess everywhere! Pants and shoes permanently stained purple. Basement floor and workbench permanently stained purple. GAAHHH!

MYSTERY #2: Why did it foam so violently when I added sugar water? I've never had that happen before!

Anyway, I siphoned the juice that remained into a 6 gallon carboy. Given the epic frothy disaster it made all over the basement, I thought I must have lost a lot of juice. But when I siphoned it from the bucket into the carboy it ended up filling the carboy about 90% full, so I'm thinking I really only lost a liter or so. I added my chosen yeast (already reconstituted), put a stopper and airlock on it and began the sticky job of cleaning up.

This morning everything seems OK - the airlock is bubbling along merrily down there. So hopefully the influence of the wild yeast is benign and everything is going to be good. But I'm just left wondering - what the heck happened??

 

[JohnT]

It could be a number of things.

It could have been the wild yeast if the wine was actively fermenting.
let me ask.. Was there a definite drop in the SG from the time that you get the juice home?

The sudden addition of sugar to active yeast can definitely cause an eruption like that.

I am not sure about the chemistry, but perhaps it could also be nucleation? A release of gas produced by the CACO3??

Perhaps a combo of the two?

 

[salcoco]

do not know the answer to number one but for number 2, the wine was fermenting; adding the sugar water provided the nuclei for the co2 gas to form and created the volcano. not uncommon occurrence during a fermentation.
A wild thought on number 1, although we think is it was a wild yeast, it was what I call a domesticated yeast, in that it was present in your supplier cellar as previously used for his fermentation. as such it evolved to be pretty resistant to sulfate, therefore it started as long as there was sugar.

 

[RonObvious]

Ah, nucleation - I'm somewhat familiar with it, but never associated sugar with the process. Makes perfect sense though - thanks for the info!

As for the wild/domesticated yeast, I guess that makes sense too. I really don't think the yeast came from my bucket, as I washed it very well before we went to the vineyard and I kept it partially filled with strong sulfite solution on the way there. I just hope it's a good yeast and won't produce any off-flavors. I guess time will tell.

Thanks again.